A curette is a surgical instrument consisting of a handle, a shaft, and a tip which is generally cup shaped, much like a small spoon, used for the purpose of scraping and scooping out various pathological (diseased) bodily tissues, such as a disc between two vertebrae. The open space of the cup-like tip has a sharpened rim to enhance its effectiveness for scraping.
In practice, the tip of the instrument is placed into the area of tissue to be removed and scraped against the tissue. When the cup is filled the instrument is removed from the wound and the tissue within the cup is then manually emptied. The instrument is then returned to the wound, where the process is performed repeatedly until the entirety of the pathological tissue has been removed.
A ring curette is a particular type of curette in which the cup is without a bottom, forming a ring. While such a curette is less useful in scooping out and removing scraped tissues, this is more than offset by its enhanced effectiveness in the more specific task of scraping the tissue free. Since the bottom of the cup is absent, the scraped tissue passes through the ring and does not accumulate in the cup, allowing the instrument to continue scraping. As large amounts of tissue once freed can more easily be removed with a surgical instrument known as a rongeur, it is more efficient to utilize the ring type curette followed by use of the rongeur, rather than using the cup type curette.
Furthermore, since the ring curette and the rongeur are more specialized to their singular purposes, they are more effective. Also, since they require less frequent passing of the instrumentation in and out of the body, with the attendant risk of internal tissue injury and wound contamination, they are also safer.